Production of aqueous polymer compositions

ABSTRACT

Process for making organic solvent-free aqueous crosslinkable polymer composition comprising: a) preparing an aqueous solution of an acid-functional olgiomer with Tg below 50° C. and having crosslinker functional groups; b) conducting an aqueous emulsion polymerisation to make an aqueous emulsion of an olefinic hydrophobic polymer in the presence of the aqueous oligomer solution, the hydrophobic polymer having Tg at least 25° C. higher than that of the oligomer and optionally crosslinker functional groups, and c) combining with a crosslinking agent reactable with the crosslinker groups of the oligomer and polymer, said composition having Koenig hardness of ≧40 sec and minimum film forming temperature (MFFT)≦55° C. Also the aqueous composition so formed and its use in various applications. The aqueous composition has excellent properties and in particular an advantageous balance of MFFT and Koenig hardness.

This application is the national phase application PCT/GB95/00948, filedApr. 27, 1995 which designated the U.S.

The present invention relates to a process for the production of certainaqueous crosslinkable polymer compositions useful for coating, to theaqueous compositions so produced, and to their use in coatingapplications.

There is an ever increasing impetus to replace or supplementsolvent-based polymer coating compositions with aqueous-basedcounterparts due to the environmental toxicity and flammability problemsposed by the use of volatile organic solvents. However, even whereaqueous-based polymer compositions have been devised, their productionhas usually entailed the intermediate use of organic solvents, requiringsubsequent removal which is costly and time-consuming, or theincorporation of a certain amount of a solvent in the final compositionwhich acts to ensure proper film-formation on coating (known as acoalescing solvent). There is therefore also now increasing pressure tosignificantly reduce or eliminate the volatile organic contents (VOC's)in aqueous-based polymer composition syntheses both as components intheir production (even if subsequently removed) and in the resultingcomposition as an aid to film coalescence.

Further still, even if one can achieve a solvent-free aqueous polymercoating composition, it has been found difficult to achieve one with abalance of good properties conventionally required in most coatingcompositions, particularly acceptably high hardness and low minimum filmforming temperature (MFFT). It should also have good water and solventresistance, and good storage stability.

We have now invented a process which enables such compositions to beprepared. In particular, the process of the invention produces in mostif not all cases in the resulting composition an exceptionallyadvantageous combination of MFFT and hardness wherein one obtains in agiven composition an exceptionally high hardness opposite the particularMFFT of that composition.

According to the present invention there is provided a process for theproduction of an organic solvent-free aqueous crosslinkable polymercomposition useful for coating, which process is organic solvent-freeand comprises:

a) preparing an aqueous solution of an acid-functional oligomer builtfrom olefinically unsaturated monomers, said oligomer having a numberaverage molecular weight Mn within the range of from 500 to 50,000(preferably 2000 to 25000), a glass transition temperature Tg below 50°C. (preferably below 20° C.), said oligomer being formed using anorganic solvent-free aqueous emulsion or aqueous solution polymerisationprocess, and said acid functionality rendering the oligomerwater-soluble per se or by neutralization, and said oligomer also havingfunctional groups for imparting crosslinkability when the aqueouspolymer composition is subsequently dried,

b) conducting an aqueous emulsion polymerization process to form anaqueous emulsion of a hydrophobic polymer from at least one olefinicallyunsaturated monomer in the presence of the aqueous solution of theoligomer, said hydrophobic polymer having a Tg which is at least 25° C.higher than the Tg of said oligomer (preferably at least 40° C. higher),and said hydrophobic polymer optionally having functional groups forimparting crosslinkability when the aqueous polymer composition issubsequently dried, and

c) combining the aqueous emulsion from b) with a crosslinking agent byaddition of the crosslinking agent after the polymerisation of step b)and/or performing the polymerisation in the presence of the crosslinkingagent, said crosslinking agent being reactable with the crosslinkerfunctional groups of the oligomer and (if present) of the hydrophobicpolymer on subsequent drying to effect crosslinking, wherein saidcrosslinking agent is not an agent which effects crosslinking by theformation of ionic bonds,

and wherein further, said polymer composition on drying has a Koenighardness of at least 40 sec (preferably within the range 60 to 200 sec)and said polymer composition has a minimum film forming temperature of ≦550° C. (preferably within the range 0° to 30° C.).

There is also provided an aqueous polymer composition which is formableby a process as defined supra.

There is further provided the use of an aqueous polymer composition asdefined supra in coating applications, and in particular in theprotective coating of substrates such as wood, plastics, metal andpaper.

The prior art discloses a number of processes in which an aqueousemulsion of a polymer system containing a low molecular weighthydrophilic polymer and a hydrophobic emulsion polymer has been producedby a multistage process and in which (often) the hydrophilic oligomerhas been solubilized in the aqueous medium.

U.S. Pat. No. 4,151,143 claims the production of surfactant-freeemulsion polymer coating compositions using a process which involves (1)a first stage wherein organic solution-prepared carboxyl-functionalpolymer is dispersed/solubilized in water by neutralisation and (2) asecond stage wherein a mixture of polymerisable monomers is subjected toemulsion polymerisation. The first stage polymer can be of relativelylow molecular weight, the first and/or second stage polymer isoptionally hydroxy-functional and the emulsion can be optionally mixedwith an amino-type crosslinker such as hexamethoxymethyl melamine.

U.S. Pat. No. 4,894,394 concerns the production of an invertedcore/shell latex by (1) preparing a hydrophilic low molecular weightfirst stage polymer by aqueous emulsion polymerisation; (2) conducting asecond emulsion polymerisation to produce a hydrophobic second stage;and (3) adjusting the pH of the resulting inverted core-shell emulsionto dissolve the first stage. The first and second stage monomers canoptionally include hydroxyalkyl (meth)acrylates and glycidyl(meth)acrylate although no emphasis is laid on them.

U.S. Pat. No. 4,845,149 relates to an emulsion polymer preparation(useful as a pressure sensitive adhesive) by emulsion polymerisingmonomers in the presence of an aqueous solution or dispersion of acarboxyl functional support polymer (of low molecular weight).

U.S. Pat. No. 4,904,724 (≡EP 320865) discloses that an organic solventsolution polymer system (a blend of acid-functional and acid-freepolymers) is dispersed into water with neutralisation and used as theseed for an aqueous emulsion polymerisation. The solution polymers canbe carbonyl functional in which case a crosslinker such as polyhydrazideis added.

CA 2,066,988 (≡DE 4,113,839) relates to emulsifier-free emulsionpolymerisation by polymerisation of ethylenic monomers (A) in an aqueousmedium containing a neutralised acid-containing polymer (B) (preferablywater-soluble styrene/acrylic acid copolymer of molecular weight1,000-5,000). The (A) monomers are fed to the aqueous medium duringpolymerisation and can optionally include amino or glycidyl functionalmonomers, although crosslinking per se is not mentioned.

EP 0,522,791 is concerned with redispersible polymer powders prepared bya 2-stage aqueous emulsion sequential polymerisation process to make acore/shell polymer emulsion, followed by optional spray drying. In thefirst stage a low molecular weight carboxy-functional polymer which canoptionally include up to 30% hydroxyalkyl (meth)acrylate is polymerisedin aqueous emulsion to form the shell part; this is neutralised, and inthe second stage, monomers, which can again optionally include up to 30%hydroxyalkyl ester, are polymerised to form the core part, and theaqueous emulsion of core/shell polymer optionally converted by spraydrying into a redispersible polymer powder. The core and shell arepreferably grafted together in the emulsion by the use of polyfunctionalcompounds such as allyl methacrylate. The disclosure is silent as to theuse of a crosslinking agent to effect curing after any coatingformation.

EP 0,587,333 is directed to water-resistant multi-stage polymer aqueousemulsions having an alkali-insoluble polymer and dissolvedalkali-soluble, acid-functional oligomer. They are made by sequentialaqueous emulsion polymerisation of a monomer system for the oligomer,including an acid functional monomer and optionally a polyfunctionalcompound, followed by that of a monomer system for the alkali-insolublepolymer optionally including an amine-functional monomer. The purpose ofthe polyfunctional compound, or the amine functionality of thealkali-insoluble polymer is to cause physical or chemical interactionbetween the alkali-soluble oligomer and alkali-insoluble polymer whilepresent in the emulsion, e.g. by grafting together of the two phaseswhile forming the final emulsion. Additionally, the aqueous emulsion canincorporate metal ions such as those of Zn, Mg, and Ca so as to createionic metal/carboxylate crosslinks, which would occur after coatingformation from the emulsion. The alkali-soluble oligomer is solubilizedin the emulsion either by neutralizing it with a base after completingboth polymerisation stages or, less preferably by neutralizing it with abase before the commencement of the second stage polymerisation to formthe alkali-insoluble polymer.

None of the above-discussed disclosures teaches a process having theselected combination of features and integers as defined in theinvention process which are utilised to produce a composition suitablefor coating having such an advantageous combination of properties asdiscussed above.

The process of the invention results in an aqueous composition providinga polymeric coating of high hardness (as defined) on substrates such aswood, plastics, metal and paper, the aqueous composition being of lowMFFT (as defined). It also achieves coatings of good solvent and waterresistance. The process itself is organic solvent-free, as is theresulting aqueous polymer composition. The composition also has goodshelf stability.

In particular, the process of the present invention allows theproduction of compositions which at least for the most part have anexceptionally advantageous balance of MFFT and Koenig hardness whereinone obtains an unusually high Koenig hardness for the particular valueof MFFT of the composition. This is most surprising because theachievement of low MFFT and high hardness in a composition wouldnormally work against each other, i.e. if the composition has a very lowMFFT it will tend not to have a particularly high hardness, or a veryhigh hardness for the composition will not be commensurate with arelatively low MFFT.

Being aqueous-based, the lower limit of MFFT for invention compositionswill of course be the freezing point of the aqueous carrier phase. Thiswill usually be about 0° C. (perhaps slightly lower because of anydissolved constituent(s) although not usually below -20° C.). Thereforethe range of MFFT for the invention compositions will usually be about0° to 55° C., more usually 0° to 30° C. The Koenig hardness will be ≧ 40sec and more usually in the range 60 to 200 sec.

As discussed above, a particularly advantageous feature is that for most(if not all) compositions of the invention the combination of MFFT andKoenig hardness is surprisingly exceptionally advantageous. We have infact found that most (if not all) compositions of the invention(certainly those we have made thus far), fit the following empiricalequation in terms of the relationship of MFFT and Koenig hardness, whereH represents Koenig hardness (in secs) and T represents MFFT (in °C.):

    H≧1.5T+70

So, e.g. when T=0° C., H is ≧70 secs; when T is 5° C., H is ≧77.5 secs;when T is 10° C., H is ≧85° C. sec; when T is 20° C., H is ≧100° C.,when T is 40° C., H is ≧130° C. and so on.

Moreover, in all the invention compositions we have made thus far, thecombination of MFFT and Koenig hardness is even more advantageous thansuggested above and fits the empirical relationship:

    H≧1.5T+90

So, e.g. when T is 0° C., H is ≧90 secs; when T is 10° C., H is ≧105secs; when T is 40° C., H is ≧150 secs and so on.

The solubilization of the oligomer is effected before carrying out thepolymerisation of step b). Solubilization subsequent to thepolymerisation to form the hydrophobic polymer, the preferred techniquein the process of EP 0,587,333, would incur a worse MFFT/Koenig hardnessbalance as compared to solubilization prior to making the hydrophobicpolymer.

Effecting grafting (or pre-crosslinking) during the formation of theemulsion composition, as described in EP 0,587,333 would likewise resultin an inferior balance of MFFT and Koenig hardness as compared toeffecting covalent crosslinking after coating formation, as is achievedwith the compositions of the invention.

Furthermore, providing ionic crosslinking after coating formation, alsoas described in EP 0.587,333, would detract from the advantageousbalance of MFFT and Koenig hardness as achieved by the process of thepresent invention.

The process of the invention, including the stage of making theoligomer, is organic solvent-free, as is the resulting polymercomposition. While solvent-free usually means entirely solvent-free, itwill be appreciated that from a practical viewpoint it may sometimes bedifficult to exclude very small amounts of organic solvent(s), whichwould otherwise have no material effect on the process or composition,as e.g. when incorating a small amount of a commercially-obtainedadditive which might be carried in a vehicle which is at least partly anorganic solvent(s). Therefore organic solvent-free is intended to alsoextend to substantially organic solvent-free.

In step a) of the process there is formed an aqueous solution of anoligomer of Mn 500 to 50,000 and built from the polymerisation ofolefinically unsaturated monomers. The polymerisation techniqueemployed, which is organic solvent-free, may in principle be an aqueoussolution polymerisation process to produce directly an aqueous solutionof the oligomer, but is more usually a conventional aqueous emulsionpolymerisation process to form an aqueous polymer emulsion or latex.Such a process is extremely well known and need not be described ingreat detail. Suffice to say that such a process involves dispersing themonomer(s) in an aqueous medium and conducting polymerisation using afree-radical initiator (normally water soluble) and (usually)appropriate heating (e.g. 30° to 120° C.) and agitation (stirring) beingemployed. The aqueous emulsion polymerisation can be effected withconventional emulsifying agents (surfactants) being used e.g. anionicand/or non-ionic emulsifiers such as Na, K and NH₄ salts ofdialkylsulphosuccinates, Na, K and NH₄ salts of sulphated oils, Na, Kand NH₄ salts of alkyl sulphonic acids, Na, K and NH₄ alkyl sulphatessuch as Na lauryl sulphate, alkali metal salts of sulphonic acids.C₁₂₋₂₄ fatty alcohols, ethoxylated fatty acids and/or fatty amides, andNa, K and NH₄ salts of fatty acids such as Na stearate and Na oleate;aryl-containing analogues of the alkyl-containing surfactants are alsouseful; other surfactants include phosphates. The amount used ispreferably low, preferably 0.3 to 2% by weight, more usually 0.3 to 1%by weight based on the weight of total monomer(s) charged. Thepolymerisation can employ conventional free radical initiators e.g.hydrogen peroxide, t-butyl-hydroperoxide, cumene hydroperoxide,persulphates such as NH₄ persulphate, K persulphate and Na persulphate;redox systems may be used; combinations such as t-butyl hydroperoxide,isoascorbic acid and Fe EDTA are useful; the amount of initiator, orinitiator system, is generally 0.05 to 3% based on the weight of totalmonomers charged!. It will be appreciated that it is not necessary toemploy the entire amount of the oligomer prepared from polymerisation,or an aqueous solution of this entire amount, for the aqueous oligomersolution which is specified in steps a) and b) of the invention process(although it can be if desired); only a portion of it need be used forthe purposes of steps a) and b)!.

The emulsion polymerisation process when used for step a) may be carriedout using an "all-in-one" batch process (i.e. a process in which all thecomponents to be employed are present in the polymerisation medium atthe start of polymerisation) or a semi-batch process in which one ormore of the components employed (usually at least one of the monomers)is wholly or partially fed to the polymerisation medium during thepolymerisation. Although not preferred, fully continuous processes couldalso be used in principle.

The polymerisation technique employed must of course be such that a lowmolecular polymer (as defined) is formed, e.g. by employing a chaintransfer agent such as one selected from mercaptans (thiols), certainhalohydrocarbons and a-methyl styrene, as is quite conventional.

By an aqueous solution of the acid-functional oligomer may be meantherein that the oligomer is completely or substantially completelydissolved in the aqueous medium so that it is present as a truesolution. However the term also extends to the oligomer existing as adispersion in the aqueous medium (the term "water-soluble" beingsimilarly construed). In such a case the polymer dispersion is inparticular a colloidal dispersion of the polymer particles (as in apolymer latex or emulsion). Sometimes, of course, the distinctionbetween colloidal dispersions and true solutions is difficult todistinguish, a situation intermediate these states existing; or some ofthe polymer could be dispersed in the aqueous medium and some could bedissolved. Thus the term "aqueous solution" is also intended to embracea disposition of the oligomer in an aqueous medium which corresponds tosuch intermediate states.

Preferably the acid-functional oligomer contains a sufficientconcentration of acid functionality to render the polymer partially ormore preferably fully soluble in aqueous media, if necessary byneutralisation of acid groups of the polymer, as would e.g. be achievedby adjustment of the pH of the aqueous medium. (If the acid-functionaloligomer had only sufficient acid functionality to render it partiallysoluble in the aqueous medium of the emulsion, it could exist as acolloidal dispersion or intermediate between a colloidal dispersion anda true solution or could be partly dispersed and partly dissolved).Usually, the medium in which the oligomer finds itself will be acidic(pH<7) and the acid groups will be carboxyl groups so that dissolutionwill be effected by raising the pH of the medium (usually the aqueouspolymerisation medium in which the oligomer has been prepared) so as toneutralize the acid groups by the addition of a base, such as an organicor inorganic base, examples of which include organic amines such astrialkylamines (e.g. triethylamine, tributylamine), morpholine andalkanolamines, and inorganic bases such as ammonia, NaOH, KOH, and LiOH.Of course, the aqueous medium containing the acid functional oligomermay already be alkaline (or sufficiently alkaline) such that the acidgroups (such as carboxyl groups) become neutralized without therequirement for positively adding a base to raise pH, or the acid groupsmay be or include very strong acid groups such as sulphonic acid groups(pK 1 to 2) so that neutralisation may not be necessary to achievedissolution. Further still, it is possible for acid monomers to bepolymerised in salt form rather than as the free acid.

The aqueous emulsion polymerisation of step b) yields a hydrophobicemulsion polymer, this type of polymer being well understood by thoseskilled in the art. Generally speaking it may be considered herein as awater-insoluble polymer whose water-insolubility is maintainedthroughout the pH range. The hydrophobic nature of the polymer isachieved by virtue of the polymer containing a sufficient concentrationof at least one hydrophobic monomer (i.e. in polymerised form) to renderthe polymer hydrophobic and water-insoluble throughout the pH range.Thus the emulsion polymer formed in the emulsion polymerisation processof step b) is insoluble in the aqueous medium of that polymerisationprocess regardless of any adjustments in pH to which the medium could besubjected.

The monomer system used for the preparation of the acid functionaloligomer is any suitable combination of olefinically unsaturatedmonomers which is amenable to copolymerisation provided such a monomersystem includes an acid-bearing comonomer(s) (preferably in sufficientconcentration to render the resulting polymer fully or partially solublein aqueous media as discusses supra), or a comonomer(s) bearing anacid-forming group which yields, or is subsequently convertible to, suchan acid group (such as an anhydride, e.g. methacrylic anhydride ormaleic anhydride, or an acid chloride) and also a comonomer(s) whichimparts crosslinkability. Typically the acid-bearing comonomers arecarboxyl-functional acrylic monomers or other ethylenically unsaturatedcarboxyl bearing monomers such as acrylic acid, methacrylic acid,itaconic acid and fumaric acid. Sulphonic acid-bearing monomers couldalso e.g. be used, such as styrene p-sulphonic acid (or correspondinglystyrene p-sulphonyl chloride). An acid bearing monomer could bepolymerised as the free acid or as a salt, e.g. the NH₄ or alkali metalsalts of ethylmethacrylate-2-sulphonic acid or2-acrylamido-2-methylpropane sulphonic acid, or the corresponding freeacids. Other, non-acid functional non-crosslinking monomer(s) which maybe copolymerized with the acid monomer(s) include acrylate andmethacrylate esters and styrenes; also dienes such as 1,3-butadiene andisoprene, vinyl esters such as vinyl acetate, and vinyl alkanoates.Methacrylates include normal or branched alkyl esters of C1 to C12alcohols and methacrylic acid, such as methyl methacrylate, ethylmethacrylate, and n-butyl methacrylate, and (usually C5 to C12)cycloalkyl methacrylates acid such as isobornyl methacrylate andcyclohexyl methacrylate. Acrylates include normal and branched alkylesters of C1 to C12 alcohols and acrylic acid, such as methyl acrylate,ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate, and(usually C5 to C12) cycloalkyl acrylates such as isobornyl acrylate andcyclohexylacrylate. Styrenes include styrene itself and the varioussubstituted styrenes, such as α-methyl styrene and t-butyl styrene.Nitriles such as acrylonitrile and methacrylonitrile may also bepolymerised, as well as olefinically unsaturated halides such as vinylchloride, vinylidene chloride and vinyl fluoride. Functional monomerswhich impart crosslinkability (crosslinking monomers for short) includeepoxy (usually glycidyl) and hydroxyalkyl (usually C1 to C12 e.g.hydroxyethyl) methacrylates and acrylates, as well as keto and aldehydefunctional monomers such as acrolein, methacrolein, and vinyl methylketone, the acetoacetoxy esters of hydroxyalkyl (usually C1 to C12)acrylates and methacrylates such as acetoacetoxyethyl methacrylate andacrylate, and also keto-containing amides such as diacetone acrylamide.The purpose of using such functional monomer is to provide subsequentcrosslinkability in the resulting polymer system as discussed. (Inprinciple the functional monomer used for imparting crosslinkabilitycould be acid-bearing monomer, but this is not usual).

Typically, the acid functional oligomer is derived from a monomer systemwhich contains 1-45 weight % of acid comonomer(s), preferably 3-30weight % and more preferably 3-20 weight %; 0.5 to 20 weight %,preferably 1 to 15 weight %; and particularly 1 to 10 weight % ofcrosslinking monomer(s); and 98.5-50 weight % of non acid functional,non-crosslinking comonomer(s), preferably 96-65 weight %, and morepreferably 96-75 weight %. The non acid functional, non-crosslinkingcomonomer(s) in some cases is usefully selected from one or more ofmethyl methacrylate, styrene, ethyl acrylate, n-butyl methacrylate,2-ethyl hexyl acrylate and n-butyl acrylate while the acid monomer isfor example methacrylic acid and/or acrylic acid. Useful oligomers ofthis type are derived from a monomer system which contains 3-12 weight %methacrylic acid and/or acrylic acid, 1 to 10 weight % of diacetoneacrylamide and/or acetoacetoxy ethyl methacrylate, 10-30 weight % methylmethacrylate, 30-70 weight % of n-butyl acrylate, 0-40 weight % of oneor more of ethyl acrylate, 2-ethylhexyl acrylate and n-butylmethacrylate and 0-40 weight % styrene.

The oligomer from step a) should have a number average molecular weightwithin the range of from 500-50,000, preferably 2000-25,000 andparticularly 3,000-19,000. (Polymer molecular weights may be determinedby gel permeation chromatography calibrated using an appropriate knownpolymer as standard). The Tg of the oligomer is below 50° C., preferablybelow 20° C. Tg will not normally be below -75° C. (and usually notbelow -50° C.). A preferred range for Tg is -75° C. to <50° C., morepreferred -50° C. to <20° C.

The aqueous emulsion polymerisation process employed in step b) to formthe hydrophobic polymer, may, apart from the incorporation of the acidfunctional oligomer from step a), be that of a conventional aqueousemulsion polymerisation process and basically as described above whendiscussing the use of such a process for-the preparation of theacid-functional oligomer. However, an important preferred feature of theinvention is that it is often possible to eliminate or much reduce therequirement for the addition of a surfactant to act as an emulsifier inthe polymerisation of step b), because the acid functional oligomeritself can fulfil such a function (i.e. act as an emulsifying agent).Thus the aqueous emulsion resulting from step b) preferably contains avery low level of such added emulsifier (surfactant), with usually lessthan 0.5% (preferably less than 0.25%, and often zero) based on thetotal weight of monomers charged being used, and with the onlysurfactant present preferably being that remaining from the oligomerpolymerisation (not counting the oligomer itself). In fact the overalllevel of surfactant (not counting the oligomer itself) is preferably <1%more preferably <0.5%, particularly <0.35%, based on the total weight ofmonomers charged for the hydrophobic polymer.

The monomer system employed for the formation of the hydrophobic polymermust be such that the resulting polymer is hydrophobic as described.Similar non acid functional, non crosslinking monomers to those used formaking the oligomer may be employed, and in particular styrenes, such asstyrene itself, α-methlystyrene, o-, m- and p-methylstyrene, o-, m- andp-ethylstyrene, p-chlorostyrene and p-bromostyrene; normal and branchedacrylic and methacrylic esters of alkanols (usually 1-12C) andcycloalkanols (usually C5-C12) such as methyl methacrylate, ethylmethacrylate, n-butyl methacrylate, t-butyl methacrylate, 2-ethylhexylmethacrylate, isobornyl methacrylate and cyclohexyl methacrylate and thecorresponding acrylates; vinyl esters such as vinyl acetate and vinylalkanoates; vinyl halides such as vinyl chloride; vinylidene halidessuch as vinylidene chloride; dienes such as 1,3-butadiene andisoprene--but of course their selection must be such as to provide aresulting Tg which is at least 25° C. above that of the oligomer. Afunctional monomer(s) for imparting crosslinkability (which is notnormally an acid monomer) may optionally be included, examples of whichinclude hydroxy and epoxy functional (meth)acrylates such ashydroxyalkyl (usually C1-C12) methacrylate e.g. 2-hydroxyethylmethacrylate, glycidyl methacrylate, and the corresponding acrylates, aswell as keto- and aldehyde-functional monomers such as acrolein,methacrolein and methyl vinyl ketone, acetoacetoxy esters ofhydroxyalkyl (usually C1-C12) acrylates and methacrylates such asacetoacetoxyethyl acrylate and methacrylate, and also keto oraldehyde-containing amides such as diacetone acrylamide.

Acid functional monomers could also be included as comonomers (e.g.acrylic or methacrylic acid), although at such a level (depending ontheir nature) as to not affect the hydrophobic character of theresulting polymer. Generally speaking, the monomer system used to makethe hydrophobic polymer will usually contain less than 5 weight % of anyacid-functional monomer(s) (no matter of what type), and preferably lessthan 2 weight %, and in some preferred embodiments none at all.

The hydrophobic polymer is in some cases usefully made from a monomersystem which comprises at least one of C₁₋₁₀ -alkyl methacrylate (suchas n-butyl methacrylate), and C₃₋₁₀ -alkyl acrylate (such as n-butylacrylate), and usually diacetone acrylamide and/or acetoacetoxy ethylmethacrylate.

The polymerisation to make the hydrophobic polymer could be carried outusing a chain transfer agent, but (unlike in the preparation of theoligomer) is usually effected without the use of such a material.

The number average molecular weight of the hydrophobic polymer isusually ≧50,000, more usually ≧100,000. The upper limit does not usuallyexceed 5,000,000.

The Tg of the hydrophobic polymer should be at least 25° C. higher, morepreferably at least 40° C. higher than the Tg of the oligomer. Usually,the Tg of the hydrophobic polymer will be within the range of from -10°to 120° C., more usually from 20° to 110° C.

The aqueous solution of the oligomer of step a) is present during theemulsion polymerisation of step b) to make the hydrophobic polymer.

The presence of the oligomer in the polymerisation of step b) can beeffected in various ways, with the following being exemplary.

In one embodiment the aqueous solution of the oligomer is admixed withall of the monomers to be used in the formation of the hydrophobicpolymer and an otherwise conventional "all-in-one" batch polymerisation(with no further addition of monomer(s)) is carried out to make thelatter.

In another embodiment, the polymerisation is basically still a batchone, with all of the oligomer solution being present in thepolymerisation vessel prior to the start of polymerisation with some ofthe monomer system for the hydrophobic polymer, with the remainder ofthe monomer system for the hydrophobic polymer being added quickly inone addition a while after the polymerisation has commenced.

In a further embodiment, the polymerisation is still basically a batchone, with all of the oligomer solution being present in thepolymerisation vessel prior to the start of the polymerisation, but themonomer system for the hydrophobic polymer is now split into severalequal parts (batches). These parts are added and polymerised consecutiveto one another in order to obtain more control over the polymerisation;therefore effectively it is a polybatch method.

In other embodiments, semi-batch processes are employed in which part(or none) of the monomer system for the hydrophobic polymer is presentprior to the start of polymerisation in the polymerisation reactionvessel and part (or the entire amount) is fed to the reaction medium inthe polymerisation vessel during the course of polymerisation.

In one such embodiment, the aqueous oligomer solution is present (inpart) in the reaction medium for the polymerisation while part of theaqueous oligomer solution is mixed with the entire monomer system forthe hydrophobic polymer (acting as an emulsifier) and the latter fed tothe reaction medium in the polymerisation vessel during thepolymerisation.

In another embodiment, the entire oligomer solution is present in thereaction vessel prior to the start of polymerisation and the entiremonomer system for the hydrophobic polymer is fed to the vessel duringthe polymerisation, i.e. there is no oligomer present in the monomerfeed.

In a further embodiment, all of the aqueous oligomer solution is presentin the reaction vessel prior to the start of the polymerisation togetherwith part of the monomer system for the hydrophobic polymer, and theremainder of the monomer system fed during polymerisation (i.e. withoutoligomer in the feed).

In a still further embodiment part of the oligomer solution is presentin the reaction vessel prior to start of the polymerisation togetherwith part of the monomer system for the hydrophobic polymer, and theremainder of the monomer system admixed with the remainder of theoligomer solution is fed during polymerisation.

In at least some embodiments of the invention, it is believed that theaqueous emulsion produced after the formation of the hydrophobic polymermay be in the form of an "inverted core-shell" latex, in which thehydrophobic polymer has formed a core domain in the oligomer--witholigomer encapsulating the hydrophobic polymer particles or forming ashell round them, or carrying the hydrophobic polymer particles in itsswollen matrix. Alternatively, it may be more realistic to speak of theoligomer simply in terms of being a seed for the polymerisation processto form the hydrophobic polymer--irrespective of the actual structure ofthe resulting polymer system that is produced, of which we are notentirely certain. Accordingly, we do not wish to be bound by anyphysical structure which might be assumed or proposed for the resultingaqueous latex of the polymer system of the invention.

Preferably the amount of crosslinking agent in step c) that is employedis such that the ratio of the number of crosslinker groups present inthe oligomer and (if employed) in the hydrophobic polymer to the numberof reactive groups (for crosslinking purposes) in the crosslinking agentis within the range of from 10/1 to 1/3, preferably 2/1 to 1/1.5.

The crosslinker in step c) is usually combined with the aqueous emulsionfrom step b) by adding thereto after the polymerisation of step b)(sometimes just before use of the composition), although it may inprinciple also be combined by performing the polymerisation of step b)in the presence of the crosslinking agent, i.e. steps c) and b) becomecombined. A combination of both incorporation expedients may also inprinciple be used.

It is a preferred feature of the invention that the low molecular weightof the oligomer produced in step a) is achieved using a process which isother than that known to the art as catalytic chain transferpolymerisation, the use of which is not usual in the process of thisinvention, although it may in principle be used. This process is thatwhere a low molecular weight polymer is produced using the technique ofradical polymerisation, using a free-radical initiator, in whichmolecular weight is controlled using a catalytic amount of a transitionmetal complex, and in particular a cobalt chelate complex, thistechnique being known in the art as a catalytic chain transfer (CCT)polymerisation. Such a technique has been described fairly extensivelyin the literature within the last decade or so. For example, variousliterature references, such as N. S. Enikolopyan et al, J.Polym.Sci.,Polym.Chem.Ed., Vol 19, 879 (1981), disclose the use of cobalt IIporphyrin complexes as chain transfer agents in free radicalpolymerisation, while U.S. Pat. No. 4,526,945 discloses the use ofdioxime complexes of cobalt II for such a purpose. Various otherpublications, e.g. U.S. Pat. No. 4,680,354, EP-A-0196783 andEP-A-0199436, describe the use of certain other types of cobalt IIchelates as chain transfer agents for the production of oligomers ofolefinically unsaturated monomers by free-radical polymerisation.WO-A-87/03605 on the other hand claims the use of certain cobalt IIIchelate complexes for such a purpose, as well as the use of certainchelate complexes of other metals such as iridium and rhenium. Finally,copending application PCT/GB94/01692 (publication WO-A-95/0476 published16.2.95) discloses a process for the preparation of an aqueous polymeremulsion which in one embodiment comprises a) preparing an aqueoussolution of an acid-functional oligomer using a CCT polymerisationprocess and b) conducting an aqueous emulsion polymerisation to form ahydrophobic polymer in the presence of the oligomer solution. Both theoligomer and hydrophobic polymer may optionally include crosslinkergroups and the composition can optionally include crosslinker groups andthe composition can optionally include a crosslinking agent. Thedisclosure does not discuss or teach a process having the selection offeatures and integers as defined in the invention process. Inparticular, none of the example compositions include an oligomer withcrosslinker groups, none have oligomers with Tg below 50° C., and nonehave hydrophobic polymers with Tg calculated to be at least 25° C.higher than the Tg of the oligomer.

It will be appreciated that the oligomer and optionally the hydrophobicpolymer possess functional groups for imparting latent crosslinkabilityto the composition (i.e. so that crosslinking takes place e.g. after theformation of a coating therefrom) when combined with the crosslinkingagent in step c). For example, one or both polymers could carryfunctional groups such as hydroxyl groups and the compositionsubsequently formulated in step c) with a crosslinking agent such as apolyisocyanate, melamine, or glycoluril; or the functional groups on oneor both polymers could include keto or aldehyde carbonyl groups and thesubsequently formulated crosslinker in step c) could be a polyamine orpolyhydrazide such as adipic acid dihydrazide, oxalic acid dihydrazide,phthalic acid dihydrazide, terephthalic acid dihydrazide, isophoronediamine and 4,7-dioxadecene-1,10 diamine. It will be noted that suchcrosslinking agents will effect crosslinking with the functionalcrosslinker groups of the oligomer and also of the hydrophobic polymer(if present) by virtue of forming covalent bonds, and are notcrosslinking agents which would effect crosslinking by virtue of theformation of ionic bonds, as e.g. by the addition of metal ions to reactwith polymer-bound carboxylate ions.

The minimum film forming temperature (MFFT) of a composition as usedherein is the temperature where the composition forms a smooth andcrackfree coating or film using DIN 53787 and applied using a Sheen MFFTbar SS3000.

Koenig hardness as used herein is a standard measure of hardness, beinga determination of how the viscoelastic properties of a film formed fromthe composition slows down a swinging motion deforming the surface ofthe film, and is measured according to DIN 53157 NEN5319.

As is well known, the glass transition temperature of a polymer is thetemperature at which it changes from a glassy, brittle state to aplastic, rubbery state.

The solids content of an aqueous composition of the invention is usuallywithin the range of from about 20 to 65 wt % on a total weight basis,more usually 30 to 55wt %. Solids content can, if desired, be adjustedby adding water or removing water (e.g. by distillation orultrafiltration).

The relative amounts of the oligomer and the hydrophobic polymer in theaqueous polymer composition are preferably such that the weight % of theoligomer, based on the weight of the oligomer plus the hydrophobicpolymer in the polymer composition, is preferably within the range offrom 1 to 70 weight %, more preferably 5 to 50 weight %.

The aqueous compositions of the invention may be used in variousapplications and for such purposes may be further optionally combined orformulated with other additives or components, such as defoamers,rheology control-agents, thickeners, dispersing and stabilizing agents(usually surfactants), wetting agents, fillers, extenders, fungicides,bacteriocides, coalescing and wetting solvents (although solvents arenot normally required), plasticisers, anti-freeze agents, waxes andpigments.

The aqueous compositions may e.g. be used, appropriately formulated ifnecessary, for the provision of films, polishes, varnishes, lacquers,paints, inks and adhesives. However, they are particularly useful andsuitable for providing the basis of protective coatings for woodensubstrates (e.g. wooden floors), and plastics, paper and metalsubstrates.

The compositions once applied may be allowed to dry naturally at ambienttemperature, or the drying process may be accelerated by heat.Crosslinking can be developed by allowing to stand for a prolongedperiod at ambient temperature (several days) or by heating at anelevated temperature (e.g. 50° C.) for a much shorter period of time.

The present invention is now further illustrated, but in no way limited,by reference to the following examples. Unless otherwise specified allparts, percentages, and ratios are on a weight basis.

The glass transition temperatures of the oligomers in the examples usethe values in °C. determined experimentally using differential scanningcalorimetry DSC, taking the peak of the derivative curve as Tg, orcalculated from the Fox equation (as for the hydrophobic polymers--seefollowing).

The glass transition temperatures of the hydrophobic polymers in theexamples were calculated by means of the Fox equation. Thus the Tg, indegrees Kelvin, of a copolymer having "n" copolymerised comonomers isgiven by the weight fractions W of each comonomer type and the Tg's ofthe homopolymers (in degrees Kelvin) derived from each comonomeraccording to the equation: ##EQU1##

The calculated Tg in degrees Kelvin may be readily converted to °C. (Ifthe hydrophobic polymer is a homopolymer, its Tg is simply that of thepolymerised monomer--normally available from the literature).

In the examples the following abbreviations are used.

    ______________________________________    AP        ammonium persulphate    BA        n-butylacrylate    t-BHPO    tert-butyl hydroperoxide    BMA       n-butylmethacrylate    DAAM      diacetone acrylamide    EDTA      ethylenediamine tetraacetic acid    LMKT      lauryl mercaptan (chain transfer agent)    MAA       methacrylic acid    MMA       methylmethacrylate    3-MPA     3-mercapto propionic acid (chain transfer agent)    SLS       sodium lauryl sulphate    TM        total monomers    s/s       solids/solids    SA        stoichiometric amount    FM        free monomer content    ADH       adipic acid dihydrazide    ALMA      allyl methacrylate    RT        room temperature    ______________________________________

The recipe and procedure for the preparation of an aqueous solution ofan acid-functional oligomer A for use in the invention process is asfollows.

Recipe for Oligomer A

Composition BA/MMA/MAA/DAAM=60/24/8/8

Akyposal SLS (sodium lauryl sulphate emulsifying agent): 0.5% on TM(s/s) 25% in the reactor; 75% in the feed

AP: 0.3% on TM (s/s). Added as a separate feed during emulsionpolymerisation (solids of the feed is 1.5% in demin. water)

LMKT: 1.6% on TM (in the feed)

3-MPA: 0.8% on TM (in the feed)

Neutralisation: 2 SA NH₃

Solids of the neutralized solution: 27.5%

    ______________________________________    Logsheet and procedure for the preparation of oligomer A    Nr       Component         Amount (g)    ______________________________________    1        H.sub.2 O (demin) 876.49    2        Akyposal SLS       2.00    3        AP (1.5% (s/s) in demin water)                                95.93    4        H.sub.2 O         207.07    5        Akyposal SLS       6.00    6        LMKT               7.67    7        3-MPA              3.84    8        BA                287.79    9        MMA               115.12    10       MAA                38.37    11       DAAM               38.37    12       NH.sub.3  (12.5%) 121.36    ______________________________________

Charge 1 and 2 to the reactor. Heat the reactor contents to 70° C. andadd 5% of the preemulsified feed 4-11. Heat the reactor contents to 80°C. Add 30% of 3 to the reactor. Keep the reactor contents for 5 minutesat 80° C. Start feeding the preemulsified feed 4-11 and the initiatorfeed 3. The reaction temperature is 85±2° C. The monomer feed shouldtake 60 minutes, the initiator feed should take 70 minutes. Keep thereactor contents at 85° to 90° C. for 30 minutes. Cool down to 80° C.and add 12 slowly (the viscosity increased although there was notcomplete dissolution). Keep the reactor contents at 80±20° C. foranother 30 minutes. Cool down to 25° C.

Specifications

solids (%): 26.8

pH: 9.8

viscosity (mpas at 25° C.): 18000

sediment after sieving (%): 0.15

FM (%): <0.1

Tg (measured by DSC) (°C.): 0

Mn: 9600

d: 2.5

EXAMPLE 1

The recipe and procedure for the preparation of an invention compositionby the "batch" method is as follows.

Recipe

Composition

Oligomer Part: see Oligomer A above Polymer part: MMA/BMA/DAAM/53/43/4Tg (polymer part, calculated) (°C.); 62° C.

Oligomer/polymer (s/s): 100/100 (=50/50) All oligomer in the reactor.

Monomer mixture and initiator system added in three parts with ratio34/33/33 t-BHPO: 0.26% on TM. Added to the reactor as a 30% (s/s) slurryin demin. water. i-Ascorbic acid: 0.05% on TM. Added to the reactor as a1% (s/s) solution in demin water. FeEDTA: 0.01% on TM. Added to thereactor as a 1% (s/s) solution in demin. water. i-Ascorbic acid: 0.21%on TM. Added as a feed (1% (s/s) solution in demin. water).

Solids: 37.5%.

    ______________________________________    Logsheet and procedure for the preparation of the    composition of Example 1    Nr     Component             Amount (g)    ______________________________________     1     H.sub.2 O             88.29     2     oligomer A solution   900.38     3     t-BHPO 30% (s/s) in demin. water)                                  0.72     4     i-ascorbic acid (1% (s/s) in demin. water)                                  4.13     5     FeEDTA (1% (s/s) solution*)                                  1.08     6     i-ascorbic acid (1% (s/s) in demin.water)                                 17.36     7     MMA                   43.81     8     BMA                   35.54     9     DAAM                   3.31    10     t-BHPO (30% (s/s) in demin. water)                                  0.70    11     i-ascorbic acid (1% (s/s) in demin. water)                                  4.01    12     FeEDTA (1% (s/s) solution*)                                  1.04    13     i-ascorbic acid (1% (s/s) in demin. water)                                 16.85    14     MMA                   42.52    15     BMA                   34.50    16     DAAM                   3.21    17     t-BHPO (30% (s/s) in demin. water)                                  0.70    18     i-ascorbic acid (1% (s/s) in demin. water)                                  4.01    19     FeEDTA (1% (s/s) solution*)                                  1.04    20     i-ascorbic acid (1% (s/s) in demin. water)                                 16.85    21     MMA                   42.52    22     BMA                   34.50    23     DAAM                   3.21    24     H.sub.2 O             10.00    25     ADH                   13.40    ______________________________________     *Made from FeSO.sub.4, EDTA, NaOH and demin. water.

Charge 1 and 2 to the reactor. Add 7-9 to the reactor and heat the batchto 35° C. Keep the batch at this temperature for 30 minutes. Add 3-5 tothe reactor. The temperature of the batch will rise. Keep the batch atthe peak temperature for 15 minutes. Feed 6 in 30 minutes into thereactor. Let the temperature drift during the feeding of 6 and 15minutes afterwards. Cool down to 35° C. Add 14-16 to the reactor andkeep the batch at 35° C. for 15 minutes. Add 10-12, the temperature willrise. Keep the batch at peak temperature for 15 minutes. Feed 13 intothe reactor in 30 minutes. Let the temperature drift during the additionand 15 minutes afterwards. Cool down to 35° C. Add 21-23 to the reactor.Keep the batch at 35° C. for 30 minutes. Add 17-19, the temperature willrise. Keep the batch at peak temperature for 15 minutes. Feed 20 intothe reactor in 30 minutes. Let the temperature drift during the additionand 15 minutes afterwards. Add 25 at 40°-45° C., followed by 24. Keepthe batch at 40°-45° C. for 30 minutes and cool down to 25° C.

Specifications

hardness (Koenig) (sec): 128

MFFT (°C): 0

EXAMPLE 2

The recipe and procedure for the preparation of an invention compositionby the "batch" method is as follows.

Recipe

Composition

Oligomer part: see Oligomer A Polymer part: MMA/BMA/DAAM =51.64/45.36/3.Tg (polymer part, calculated) (°C.): 60° C.

oligomer/polymer (s/s): 60/100 (=37.5/62.5). All oligomer in thereactor.

Monomer mixture and initiation system added in three parts with ratio34/33/33/ t-BHPO: 0.26% on TM. Added to the reactor as a 30% (s/s)slurry in demin. water. i-Ascorbic acid: 0.05% on TM. Added to thereactor as a 1% (s/s) solution in demin. water. FeEDTA: 0.01% on TM.Added to the reactor as a 1% (s/s) solution in demin. water. i-Ascorbicacid: 0.21% on TM. Added as a feed (1% (s/s) solution in demin. water).

Solids: 37.5%.

    ______________________________________    Logsheet and procedure for the preparation of the    composition of Example 2    Nr     Component             Amount (g)    ______________________________________     1     H.sub.2 O             272.60     2     oligomer A solution   778.66     3     t-BHPO (30% (s/s) in demin. water)                                 1.02     4     i-ascorbic acid (1% (s/s) in demin. water)                                  5.957     5     FeEDTA (1% (s/s) solution.sup.1)                                 1.55     6     i-ascorbic acid (1% (s/s) in demin.water)                                 25.02     7     MMA                   61.52     8     BMA                   54.04     9     DAAM                  3.57    10     t-BHPO (30% (s/s) in demin. water) 0.70                                 1.00    11     i-ascorbic acid (1% (s/s) in demin. water)                                 5.78    12     FeEDTA (1% (s/s) solution*)                                 1.50    13     i-ascorbic acid (1% (s/s) in demin. water)                                 24.28    14     MMA                   59.71    15     BMA                   52.45    16     DAAM                  3.47    17     t-BHPO (30% (s/s) in demin. water)                                 1.00    18     i-ascorbic acid (1% (s/s) in demin. water)                                 5.78    19     FeEDTA (1% (s/s) solution*)                                 1.50    20     i-ascorbic acid (1% (s/s) in demin. water)                                 24.28    21     MMA                   59.71    22     BMA                   52.45    23     DAAM                  3.47    24     H.sub.2 O             10.00    25     ADH                   9.77    ______________________________________     *Made from FeSO.sub.4, EDTA, NaOH and demin. water.

Charge 1 and 2 to the reactor. Add 7-9 to the reactor and heat the batchto 35° C. Keep the batch at this temperature for 30 minutes. Add 3-5 tothe reactor. The temperature of the batch will rise. Keep the batch atthe peak temperature for 15 minutes. Feed 6 in 30 minutes into thereactor. Let the temperature drift during the feeding of 6 and for 15minutes afterwards. Cool down to 35° C. Add 14-16 to the reactor andkeep the batch at 35° C. for 15 minutes. Add 10-12, the temperature willrise. Keep the batch at peak temperature for 15 minutes. Feed 13 intothe reactor in 30 minutes. Let the temperature drift during the additionand 15 minutes afterwards. Cool down to 35° C. Add 21-23 to the reactor.Keep the batch at 35° C. for 30 minutes. Add 17-19, the temperature willrise. Keep the batch at peak temperature for 15 minutes. Feed 20 intothe reactor in 30 minutes. Let the temperature drift during the additionand 15 minutes afterwards. Add 25 at 40°-45° C., followed by 24. Keepthe batch at 40°-45° C. for 30 minutes and cool down to 25° C.

Specification

solids (%): 37.6

pH: 9.3

viscosity (mpas at 25° C.): 615

sediment after sieving (%): 0.05

FM (%) : <0.1

hardness (Koenig) (sec): 131

MFFT (°C.: 20

The recipe and procedure for the preparation of an aqueous solution of afurther acid-functional oligomer B for use in the invention process isas follows.

Recipe for oligomer B

Composition

BA/MMA/MAA/DAAM=52.57/31.43/8/8

Akyposal SLS (sodium lauryl sulfate emulsifying agent): 0.5% on TM(s/s). 25% in the reactor; 75% in the feed.

AP:0.3% on TM (s/s). Added as a separate feed during emulsionpolymerisation (solids of the feed is 1.5% in demin. water).

LMKT: 1.6% on TM (in the feed).

3-MPA: 0.8% on TM (in the feed).

Neutralisation: 2 SA NH₃.

Solids of the neutralized solution; 27.5%.

    ______________________________________    Logsheet and procedure for the preparation of oligomer B    Nr      Component         Amount (g)    ______________________________________    1       H.sub.2 O (demin) 876.49    2       Akyposal SLS       2.00    3       AP (1.5% (s/s) in demin. water)                               95.93    4       H.sub.2 O         207.07    5       Akyposal SLS       6.00    6       LMKT               7.67    7       3-MPA              3.84    8       BA                252.16    9       MMA               150.75    10      MAA                38.37    11      DAAM               38.37    12      NH.sub.3  (12.5%) 121.36    ______________________________________

Charge 1 and 2 to the reactor. Heat the batch to 70° C. and add 5% ofthe preemulsified feed 4-11. Heat the batch to 80° C. Add 30% of 3 tothe reactor. Keep the batch for 5 minutes at 80° C. Heat the batch to85° C. Start feeding the preemulsified feed 4-11 and the initiator feed3. The reaction temperature is 85±20° C. The monomer feed should take 60minutes, the initiator feed should take 70 minutes. Keep the batch at85° to 90° C. for 30 minutes. Cool down to 80° C. and add 12 slowly (theviscosity increased although there was not complete dissolution). Keepthe batch at 80±2° C. for another 30 minutes. Cool down to 25° C.

Specifications

solids: 27.5

pH: 9.5

viscosity (mpas at 25° C.): 176000

sediment after sieving (%): 0.10

FM (%): <0.10

Tg (measured by DSC) (°C.): 10

EXAMPLE 3

The recipe and procedure for the preparation of an invention compositionby the "batch" method is as follows.

Recipe

Composition

Oligomer part: See Oligomer B above. Polymer part: MMA/BMA/DAAM=51.64/45.36/3/ Tg (polymer part, calculated) (°C.); 60° C.

Oligomer/polymer (s/s): 60/100 (=37.5/62.5) All oligomer in the reactor.

Monomer mixture and initiation system added in three parts with ratio34/33/33 t-BHPO; 0.26% on TM. Added to the reactor as a 30% (s/s) slurryin demin. water. i-Ascorbic acid: 0.05% on TM. Added to the reactor as a1% (s/s) solution in demin. water. FeEDTA: 0.01% on TM. Added to thereactor as a 1% (s/s) solution in demin. water. i-Ascorbic acid; 0.21%on TM. Added as a feed (1% (s/s) solution in demin. water).

Solids: 37.5%.

    ______________________________________    Logsheet and procedure for the preparation of the    composition of Example 3    Nr     Component             Amount (g)    ______________________________________     1     H.sub.2 O             272.60     2     oligomer B solution   778.66     3     t-BHPO (30% (s/s) in demin. water)                                 1.03     4     i-ascorbic acid (1% (s/s) in demin. water)                                  5.957     5     FeEDTA (1% (s/s) solution.sup.1)                                 1.55     6     i-ascorbic acid (1% (s/s) in demin.water)                                 25.02     7     MMA                   61.52     8     BMA                   54.04     9     DAAM                  3.57    10     t-BHPO (30% (s/s) in demin. water) 0.70                                 1.00    11     i-ascorbic acid (1% (s/s) in demin. water)                                 5.78    12     FeEDTA (1% (s/s) solution*)                                 1.50    13     i-ascorbic acid (1% (s/s) in demin. water)                                 24.28    14     MMA                   59.71    15     BMA                   52.45    16     DAAM                  3.47    17     t-BHPO (30% (s/s) in demin. water)                                 1.00    18     i-ascorbic acid (1% (s/s) in demin. water)                                 5.78    19     FeEDTA (1% (s/s) solution*)                                 1.50    20     i-ascorbic acid (1% (s/s) in demin. water)                                 24.28    21     MMA                   59.71    22     BMA                   52.45    23     DAAM                  3.47    24     H.sub.2 O             10.00    25     ADH                   9.77    ______________________________________     *Made from FeSO.sub.4, EDTA, NaOH and demin. water.

Charge 1 and 2 to the reactor. Add 7-9 to the reactor and heat the batchto 35° C. Keep the batch at this temperature for 30 minutes. Add 3-5 tothe reactor. The temperature of the batch will rise. Keep the batch atpeak temperature for 15 minutes. Feed 6 in 30 minutes into the reactor.Let the temperature drift during the feeding of 6 and for 15 minutesafterwards. Cool down to 35° C. Add 14-16 to the reactor and keep thebatch at 35° C. for 15 minutes. Add 10-12, the temperature will rise.Keep the batch at peak temperature for 15 minutes. Feed 13 into thereactor in 30 minutes. Let the temperature drift during the addition and15 minutes afterwards. Cool down to 35° C. Add 21-23 to the reactor.Keep the batch at 35° C. for 30 minutes. Add 17-19, the temperature willrise. Keep the batch at peak temperature for 15 minutes. Feed 20 intothe reactor in 30 minutes. Let the temperature drift during the additionand 15 minutes afterwards. Add 25 at 40°-45° C., followed by 24. Keepthe batch at 40°-45° C. for 30 minutes and cool down to 25° C.

Specifications

solids (%): 37.5

pH: 9.4

viscosity (mpas at 25° C.): 48

sediment after sieving (%): 0.05

FM (%): <0.10

hardness (Koenig) (sec): 160

MFFT (°C.): 22

All oligomer/polymer compositions (Examples 1, 2, and 3) were cast on"test charts" and resistances of the dried films were tested accordingto the following procedure. 80μm Wet films were cast down on test charts(Leneta Company, Form 2C) and dried for 30 minutes at room temperature,followed by 16 hours at 52° C. The charts were then cooled down to roomtemperature. Droplets of the testing liquids (water, ethanol (48% w/w),coffee and "Andy" (commonly used Dutch detergent) were placed on thecoating and covered with a glass plate. The liquids were removed after16 hours and the coatings were assessed immediately and after four hoursrecovery. "Hot pan" test was done as follows. A beaker with boilingwater was placed on the wetted coating and removed after the water hadcooled down to room temperature. Assessment of the coating was the sameas for the other tests.

O Means that the coating is very severely affected by the test. Oftencracking and/or white spots are observed.

1. Means that the coating is severely affected by the test.

2. Means that the coating is affected by the test.

3. Means that the coating is affected by the test, but not as bad as inthe former cases.

4. Means that the coating is hardly affected by the test.

5. Means that the coating is not affected at all by the test.

    ______________________________________               Ethanol               (48%              Detergent    Water      w/w)     Coffee   Andy    Hot pan    Example           i     a     i    a   i    a   i    a    i    a    ______________________________________    1      5     5     3    3   2    2   4-5  4-5  4-5  4-5    2      5     5     3    4   3    3   4-5  4-5  3    4    3      5     5     3    4   4    4   4-5  4-5  3    4    ______________________________________     i: immediately after the testing liquid has been removed.     a: after recovery.

It will be noted that all the compositions prepared by the process ofthe invention had a superb balance of MFFT and Koenig hardness,excellent water resistance, and reasonable to excellent resistance toethanol, coffee, detergent and the hot pan test.

An aqueous solution of an acid-functional oligomer C was prepared havingno crosslinker monomer for the purpose of providing subsequent covalentcrosslinking (in an oligomer/polymer composition) after coatingformation, but instead-having a difunctional monomer (ALMA) foreffecting grafting (or precrosslinking) during the formation of theoligomer/polymer composition.

Recipe for oligomer C

Composition BA/MMA/ALMA/MAA=65/24/1/10

SLS (emulsifying agent): 0.5% on TM (s/s)

AP: 0.3% on TM (1.5% in demin water)

LMKT: 2.2% on TM

    ______________________________________    Logsheet and procedure for preparation of the oligomer C    Nr      Component              Amount (g)    ______________________________________    1       H.sub.2 O              1070.6    2       AP (1.5% in demin water)                                    87.3    3       SLS (sodium lauryl sulphate 30% solids)                                    1.8    4       H.sub.2 O              188.2    5       MMA                    104.8    6       MAA                     43.7    7       BA                     283.8    8       SLS                     5.5    9       LMKT                    9.8    10      NH.sub.2  (12.5%)      138.1    11      ALMA                    4.4    ______________________________________

Charge 1 and 3 to the reactor. Heat the reactor contents to 70° C. andadd 5% of the pre-emulsified feed 4-9. Heat the reactor contents to 80°C. and charge 30% of 2 to the reactor and wait for 5 minutes. With thereactor contents at 85° C. start feeding 4-8 over a period of 60minutes. Also feed 2 over 70 minutes. Rinse the feedtank with water andkeep the reactor at 85° C. for another 30 minutes. Slowly add 11 to thereactor and keep at 80° C. for another 30 minutes. The oligomer willdissolve or partly dissolve in this time. Cool down to 25° C.

Specifications

solids: 25%

pH: 10

viscosity (mpas @ 25° C.): 775

sediment: <0.2%

FM: <100 ppm

Tg (calc. °C.): 0

EXAMPLE C4

In this comparative example, a polymer composition is prepared using theoligomer C in order to yield a product with grafting (pre-crosslinking)between the oligomer and polymer phases in the resulting emulsioncomposition (i.e. as in the preferred process of EP 0,587,333). Apolybatch procedure was used. (The composition had oligomer/hydrophobicpolymer Tg values in accordance with the requirements of the inventionprocess).

Recipe

Composition Oligomer part: Oligomer C Polymer part: MMA/BMA =54.6/45.4Tg polymer part: 60° C.

oligomer/polymer (s/s): 60/100

initiator system (tBHPO, i-ascorbic acid, FeEDTA; see table)

final solids: 30%

all oligomer in reactor.

    ______________________________________    Logsheet and procedure for preparation of Example C4    Component              Amount (g)    ______________________________________    1      Water               436.8    2      Oligomer C solution 941.9    3      MMA                 214.3    4      BMA                 178.2    5      tBHPO (30% slurry in demin water)                                3.4    6      FeEDTA (1% solution)                                5.1    7      i ascorbic acid 5% in demin water                                3.9    8      i ascorbic acid 5% in demin water                                16.4    ______________________________________

Charge 1 and 2 to the reactor and 3 and 4 to the feedtank. Heat thereactor contents to 35° C. Add 50% of 3 and 4 to the reactor and mix for30 minutes. Add 50% of 5, 6 and 7 to the reactor and the polymerisationwill start. Let the temperature drift to appr. 55° C. Keep at thistemperature for 15 minutes. Feed 50% of 8 in 30 minutes. Cool to 35° C.and repeat this procedure for the other 50% of the components. Cool toRT.

Specifications

solids: 30%

pH: 9.7

viscosity (mPas at 25° C.): 352

sediment: <0.2%

MFFT (°C.): 34

Koenig hardness: 119 sec

The balance of hardness and MFFT achieved in Example C4 may bereasonably compared with that of the invention composition of Example 2having a similar oligomer and hydrophobic polymer composition (apartfrom the DAAM in oligomer A of Ex 1 and ALMA in oligomer C of Ex C4) andalso both having a 60/100 oligomer/polymer ratio and with oligomer Tg'sin both the compositions of Examples 2 and C4 being 0° C. and thehydrophobic polymer Tg's both being 60° C.

    ______________________________________              MFFT (°C.)                      Koenig Hardness (sec)    ______________________________________    Example 2   20        131    Example C4  34        119    ______________________________________

It will be observed that the MFFT/Koenig hardness of the inventioncomposition of Example 2 is clearly superior to that of Example C4, withthat of Example 2 satisfying the relationship H≧1.5T+90, while that ofExample C4 not satisfying the relationship H>1.5T+70.

EXAMPLE C5

In this composition example, an oligomer/hydrophobic polymer compositionwith keto crosslinking groups is prepared in which the oligomer issolubilized by neutralization in the aqueous phase subsequent to thepolymerisation to form the hydrophobic polymer (instead of beforeeffecting this polymerisation--as in all the proceeding examples), thisbeing the preferred technique of EP 0,587,333 to effect solubilization.(The compositions had oligomer/hydrophobic polymer Tg values inaccordance with the requirements of the invention process).

Recipe for Example C5

Oligomer phase composition BA/MMA/DAAM/MAA=60/24/8/8 Tg (calc. °C.): 60

0.5 SLS (s/s) on TM used as surfactant 0.3 AP (1.5% solution in demin.water) used as a separate initiator feed for both phases

oligomer/polymer (s/s): 60/100

neutralization: 1 SA ammonia

    ______________________________________    Logsheet and procedure for preparation of Example C5    Nr        Component       Amount (g)    ______________________________________    1         water           796.1    2         SLS (30% solids)                               2.2    3         AP (1.5% in demin water)                              131.3    4         water           105.8    5         SLS (30% solids)                               3.3    6         LMKT            14.8    7         BA              141.8    8         MMA             56.7    9         DAAM            18.9    10        MAA             18.9    11        BMA             190.8    12        MMA             216.8    13        DAAM            12.6    14        water           90.0    15        ADH             14.6    16        NH.sub.3  (12.5%)                              59.8    17        water           10.0    ______________________________________

Charge 1 and 2 to the reactor and heat to 85° C. Pre-emulsify 4-10 andcharge 10% to the reactor. Then charge 20% of 3 to the reactor and waitfor 5 minutes. Charge the remainder of the feed (4-10) in 50 minutes andcharge 40% of 3 over a period of 60 minutes with the reactor contents at85° C. This forms the oligomer. Charge 11-13 to the feedtank and feedthis to the reactor in an additional 50 minutes. Simultaneously chargethe remainder of 3 to the reactor over a period of 60 minutes at 85° C.Rinse the feedtank with 17 and charge to the reactor. Keep at 85° C. foranother 30 minutes. This forms the hydrophobic polymer. Then slowlycharge 16 to the reactor and wait for another 30 minutes. Cool to 25° C.and add 15 to the reactor rinse with 14.

Specifications

MFFT (°C.): 48

Koenig hardness: 140 secs

solids (%): 37-38

pH 9.7

viscosity (mpas at 25° C.): 17

sediment: <0.1%

The balance of hardness and MFFT achieved in Example C5 may bereasonably compared with that of Example 2, both examples having thesame oligomer and hydrophobic polymer compositions and the sameoligomer/polymer ratios, as well as having the same oligomer Tg (0° C.)and hydrophobic polymer Tg (60° C.).

    ______________________________________               MFFT (°C.)                       Koenig hardness sec    ______________________________________    Example 2    20        131    Example C5   48        140    ______________________________________

It will be observed that the MFFT/Koenig hardness balance of Example 2is clearly superior to that of Example C5, with that of Example 2satisfying the relationship H≧1.5T+90, while that of Example C5 notsatisfying the relationship H≧1.5T+70.

We claim:
 1. Process for the production of an organic solvent-freeaqueous crosslinkable polymer composition useful for coating, whichprocess is organic solvent-free and comprises:a) preparing an aqueoussolution of an acid-functional oligomer built from olefinicallyunsaturated monomers, said oligomer having a number average molecularweight Mn within the range of from 500 to 50,000 and a glass transitiontemperature (Tg) below 50° C., said oligomer being formed using anorganic solvent-free aqueous emulsion or aqueous solution polymerisationprocess, and said acid functionality by itself or by neutralizationthereof rendering the oligomer water-soluble, and said oligomer alsohaving crosslinker functional groups for imparting crosslinkability whenthe aqueous polymer composition is subsequently dried, b) conducting anaqueous emulsion polymerization process to form an aqueous emulsion of ahydrophobic polymer from at least one olefinically unsaturated monomerin the presence of the aqueous solution of the oligomer, saidhydrophobic polymer having a Tg which is at least 25° C. higher than theTg of said oligomer, and said hydrophobic polymer optionally havingcrosslinker functional groups for imparting crosslinkability when theaqueous polymer composition is subsequently dried, and c) combining theaqueous emulsion from b) with a crosslinking agent by addition of thecrosslinking agent after the polymerisation in step b) and/or performingthe polymerisation in the presence of the crosslinking agent, saidcrosslinking agent being reactable with the crosslinker functionalgroups of the oligomer and (if present) of the hydrophobic polymer onsubsequent drying to effect crosslinking, wherein said crosslinkingagent is not an agent which effects crosslinking by the formation ofionic bonds, and wherein further, said polymer composition on drying hasa Koenig hardness of at least 40 sec and said polymer composition has aminimum film forming temperature of ≦55° C.
 2. Process according toclaim 1 wherein said oligomer has a number average molecular weight offrom 2,000 to 25,000.
 3. Process according to claim 1 wherein saidoligomer has a Tg within the range of from -75 to <50° C.
 4. Processaccording to claim 3 wherein said oligomer has a Tg within the range offrom -50° C. to <20° C.
 5. Process according to claim 1 wherein saidhydrophobic polymer has a Tg which is at least 40° C. higher than the Tgof the oligomer.
 6. Process according to claim 1 wherein said polymercomposition on drying has a Koenig hardness of from 60 to 200 secs. 7.Process according to claim 1 wherein said polymer composition has aminimum film forming temperature of from 0° to 55° C.
 8. Processaccording to claim 7 wherein said polymer composition has a minimum filmforming temperature of from 0° to 30° C.
 9. Process according to claim 1wherein the resulting composition has Koenig hardness and minimum filmforming temperature according to the following empirical relationship:

    H≧1.5T+70

where H is Koenig hardness in seconds and T is minimum film formingtemperature in °C.
 10. Process according to claim 9 wherein theempirical relationship is:

    H≧1.5T+90.


11. Process according to claim 1 wherein said oligomer is completely orpartially, dissolved in the aqueous medium in step a).
 12. Processaccording to claim 11 wherein dissolution of the oligomer is effected byneutralization of the acid groups thereof using a base.
 13. Processaccording to claim 1 wherein said oligomer is derived from anolefinically unsaturated monomer system which includes an acid-bearingcomonomer(s), or a comonomer(s) bearing an acid-forming group whichyields, or is subsequently convertible to, such an acid group, and acomonomer(s) which has a functional group(s) for impartingcrosslinkability.
 14. Process according to claim 13 wherein the acidbearing monomer(s) is selected from the group consisting ofcarboxyl-containing olefinically unsaturated monomer(s).
 15. Processaccording to claim 14 wherein the monomer(s) is selected from the groupconsisting of carboxyl-functional acrylic monomers.
 16. Processaccording to claim 14 wherein said carboxyl bearing monomer(s) isselected from the group consisting of acrylic acid, methacrylic acid,itaconic acid and fumaric acid.
 17. Process according to claim 13wherein said monomer system from which the oligomer is formed includes anon-acid functional non-crosslinking comonomer(s) selected from thegroup consisting of acrylate and methacrylate esters; styrenes, dienes,vinyl esters, nitrites, and olefinically unsaturated halides. 18.Process according to claim 17 wherein said non-acid functionalnon-crosslinking comonomer(s) is selected from the group consisting ofnormal and branched alkyl esters of C1 to C12 alcohols and acrylic acidor methacrylic acid; and cycloalkyl acrylates or methacrylates; styreneitself, α-methyl styrene and t-butylstyrene; acrylonitrile andmethacrylonitrile; vinyl chloride, vinylidene chloride and vinylfluoride; vinyl acetate and vinyl alkanoates; isoprene and1,3-butadiene.
 19. Process according to claim 13 wherein the functionalgroups for providing crosslinkability are selected from the groupconsisting of epoxy, hydroxyl, ketone and aldehyde groups.
 20. Processaccording to claim 13 wherein said comonomer(s) with functional groupsfor imparting crosslinkability is (are) selected from the groupconsisting of glycidyl acrylate and methacrylate, hydroxyalkylmethacrylates and acrylates, acrolein, methacrolein and methyl vinylketone, the acetoacetoxy esters of hydroxyalkyl acrylates andmethacrylates, and keto-containing amides.
 21. Process according toclaim 13 wherein the acid-functional oligomer is derived from a monomersystem comprising 1 to 45 weight % of acid-functional comonomer(s), 0.5to 20 weight % of crosslinking comonomer(s) and 98.5 to 50 weight % ofnon-acid functional, non-crosslinking comonomer(s).
 22. Processaccording to claim 21 wherein said oligomer is derived from a monomersystem comprising 3 to 30 weight % of acid-functional comonomer(s), 1 to15 weight % of crosslinking comonomer(s) and 96 to 65 weight % ofnon-acid functional, non-crosslinking comonomer(s).
 23. Processaccording to claim 21 wherein the acid comonomer(s) is methacrylic acidand/or acrylic acid and the non-acid functional, non-crosslinkingcomonomer(s) is selected from the group consisting of one or more ofmethyl methacrylate, styrene, ethylacrylate, n-butyl methacrylate,2-ethylhexyl acrylate and n-butyl acrylate.
 24. Process according toclaim 21 wherein said oligomer is derived from a monomer system whichcomprises 3 to 12 weight % of methacrylic acid and/or acrylic acid, 1 to10 weight % of diacetone acrylamide and/or acetoacetoxyethylmethacrylate, 10 to 30 weight % of methyl methacrylate, 30 to 70 weight% of n-butyl acrylate, 0 to 40 weight % of one or more of ethylacrylate, 2-ethylhexyl acrylate and n-butyl methacrylate and 0 to 40weight % of styrene.
 25. Process according to claim 1 wherein theaqueous emulsion polymerisation of step b), is performed using an amountof emulsifying agent(s) newly added for that step (excluding theoligomer) which is less than 0.5 weight % based on the total weight ofmonomers charged for step b).
 26. Process according to claim 1 whereinthe only emulsifying agent(s) which may be present (excluding theoligomer itself) is that remaining from the emulsifying agent(s) used inthe oligomer polymerisation of step a).
 27. Process according to anyclaim 1 wherein the oligomer formed in step a) acts as an emulsifyingagent in the polymerisation of step b).
 28. Process according to claim 1wherein the polymerisation processes in steps a) and b) are carried outin the same polymerisation vessel.
 29. Process according to claim 1wherein said hydrophobic polymer is derived from an olefinicallyunsaturated monomer system which includes a non-acid bearing,non-crosslinking monomer(s).
 30. Process according to claim 29 whereinsaid non-acid, non-crosslinking monomer(s) is selected from the groupconsisting of one or more of acrylate and methacrylate esters ofalkanols, styrenes, dienes, vinyl esters, nitriles, vinyl halides andvinylidene halides.
 31. Process according to claim 30 wherein theacrylate and methacrylate esters are normal and branched alkyl esters ofC1 to C12 alcohols and acrylic or methacrylic acid, the styrenes arestyrene itself, α-methyl styrene, o-, m- and p- methylstyrene, o-, m-and p-ethyl styrene, p-chlorostyrene, and p-bromostyrene, the dienes are1,3-butadiene and isoprene, the vinyl esters are vinyl acetate and vinylalkanoates, the vinyl halide is vinyl chloride, and the vinylidenehalide is vinylidene chloride.
 32. Process according to claim 29 whereinthe monomer system used in the preparation of the hydrophobic polymerincludes a crosslinking comonomer(s) having a functional group(s) forproviding crosslinkability selected from the group consisting of epoxy,hydroxy, ketone and aldehyde groups.
 33. Process according to claim 32wherein said crosslinking comonomer(s) is selected from the groupconsisting of one or more of glycidyl methacrylate and acrylate,hydroxyalkyl methacrylates and acrylates, the acetoacetoxy esters ofhydroxyalkyl acrylates and methacrylates, and keto-containing amides.34. Process according claim 29 wherein the monomer system used for thepreparation of the hydrophobic polymer contains less than 5 weight % ofany acid-functional comonomer.
 35. Process according to claim 34 whereinthe monomer system contains no acid-functional comonomer.
 36. Processaccording to claim 1 wherein said hydrophobic polymer is made from amonomer system comprising at least one of C1-C10 alkyl methacrylates andC3-C10alkyl acrylates, and diacetone acrylamide and/or acetoacetoxyethylmethacrylate.
 37. Process according to claim 1 wherein said hydrophobicpolymer has a number average molecular weight of at least 50,000. 38.Process according to claim 37 wherein the hydrophobic polymer has anumber average molecular weight of at least 100,000.
 39. Processaccording to claim 1 wherein the aqueous solution of the oligomer ofstep a) is admixed with all of the monomers to be used in the formationof the hydrophobic polymer and an otherwise conventional "all-in-one"batch polymerisation (with no further addition of monomer(s)) is carriedout to make the hydrophobic polymer.
 40. Process according to claim 1wherein all of the oligomer solution of step a) is present in thepolymerisation vessel used to make the hydrophobic polymer prior to thestart of polymerisation together with some of the monomer system for thehydrophobic polymer, with the remainder of the monomer system for thehydrophobic polymer being added in one addition after the polymerisationhas commenced.
 41. Process according to claim 1 wherein all of theoligomer solution of step a) is present in the polymerisation vesselused to make the hydrophobic polymer prior to the start of thepolymerisation, and the monomer system for the hydrophobic polymer issplit into several equal parts (batches), these parts being added andpolymerised consecutive to one another.
 42. Process according to claim 1wherein part (or none) of the monomer system for the hydrophobic polymeris present prior to the start of polymerisation in the polymerisationvessel used to make the hydrophobic polymer and part (or the entireamount) is fed to the reaction medium in the polymerisation vesselduring the course of polymerisation.
 43. Process according to claim 42wherein the aqueous oligomer solution of step a) is present in part inthe reaction medium for the polymerisation to make the hydrophobicpolymer while part of the aqueous oligomer solution is mixed with theentire monomer system for the hydrophobic polymer and the latter fed tothe reaction medium in the polymerisation vessel during thepolymerisation.
 44. Process according to claim 42 wherein the entireoligomer solution of step a) is present in the polymerisation vesselprior to the start of polymerisation and the entire monomer system forthe hydrophobic polymer is fed to the vessel during the polymerisation,there being no oligomer present in the monomer feed.
 45. Processaccording to claim 42 wherein all of the aqueous oligomer solution ofstep a) is present in the polymerisation vessel prior to the start ofthe polymerisation together with part of the monomer system for thehydrophobic polymer, and the remainder of the monomer system for thehydrophobic polymer fed during polymerisation, there being no oligomerin the feed.
 46. Process according to claim 42 wherein part of theoligomer solution of step a) is present in the polymerisation vesselprior to start of the polymerisation to make the hydrophobic polymertogether with part of the monomer system for the hydrophobic polymer,and the remainder of the monomer system for the hydrophobic polymeradmixed with the remainder of the oligomer solution is fed duringpolymerisation.
 47. Process according to claim 1 wherein thecrosslinking agent is selected, depending on the crosslinkingfunctionality in the oligomer and (if present) in the hydrophobicpolymer, from the group consisting of a polyisocyanate, melamine,glycoluril, a polyamine, and a polyhydrazide.
 48. Process according toclaim 1 wherein the ratio of the number of crosslinker groups present inthe oligomer and (if employed) in the hydrophobic polymer to the numberof reactive groups (for crosslinking purposes) in the crosslinking agentis within the range of from 10/1 to 1/3.
 49. Process according to claim1 wherein the solids content of the resulting aqueous composition iswithin the range of from 20 to 65 wt % on a total weight basis. 50.Process according to claim 1 wherein the relative amounts of theoligomer and the hydrophobic polymer in the resulting aqueouscomposition is such that the wt % of the oligomer, based on the wt % ofthe oligomer plus the hydrophobic polymer, is within the range of from 1to 70 wt %.